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Magnetic recording device and magnetic recording method

Active Publication Date: 2017-05-30
TDK CORPARATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a magnetic recording device with a microwave assisted magnetic head and a magnetic recording method to prevent quality deterioration in signals recorded on a magnetic recording medium. This is achieved by controlling a supply of drive current to the spin torque oscillator and the main magnetic pole based on recording current waveform data, generated based on the signals, to improve the quality of the recorded signals without lowering their quality. Overall, this technology aims to provide high-quality magnetic recording.

Problems solved by technology

However, as the magnetic grains become smaller, the magnetic grains are less thermally stable in association with their reduced volume.
Therefore, if the anisotropic magnetic field of a magnetic recording medium exceeds an acceptable value determined based on the upper limit of the recording magnetic field intensity, recording on the magnetic recording medium fails.
There is a problem that the writing operation according to a recording current of a relatively long polarity reversal interval deteriorates the bit error rate (BER) of signals recorded on the magnetic recording medium 100.
Therefore, depending on the setting of the given time interval for the recording current waveform, the direct current may be applied to the spin torque oscillator even in recording a signal corresponding to a relatively long polarity reversal interval, whereby it is difficult to solve the problem of lowered quality of signals recorded on a magnetic recording medium.

Method used

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  • Magnetic recording device and magnetic recording method

Examples

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example 1

[0109]Using the magnetic recording device having the configuration shown in FIGS. 1 to 9, signals were recorded on a magnetic disc, the signals were read with the reproducing head 1A of the microwave assisted head 1, and the SN ratios (dB) of the reproduced signals were measured. The results are shown in FIG. 13.

[0110]Here, upon recording signals, the recording current waveform data DWW as shown in FIG. 10A were created based on the signals to record, the unit drive current waveforms UOP were created as shown in FIGS. 11A and 11B, and the drive current waveform data DOPW as shown in FIG. 10B were created. The signals recorded on a magnetic disc included a signal S1 corresponding to a relatively short polarity reversal interval GPR1, a signal S3 corresponding to a relatively long polarity reversal interval GPR3, and a signal S2 corresponding to a polarity reversal interval GPR2 in-between. The relationship between the threshold time TH for creating the drive current waveform data DOP...

reference example 1

[0113]Signals were recorded on a magnetic disc in the same manner as in Example 1 except that no drive current IOP was applied while recording the signals. The signals were read with the reproducing head 1A of the microwave assisted head 1, and the SN ratios (dB) of the reproduced signals were measured. The results are shown in FIG. 13.

[0114]FIG. 13 is a graph showing the SN ratios (dB) of the signals S1 to S3. The results shown in FIG. 13 confirmed that it is possible to improve the SN ratio of the signal S1 corresponding to a relatively short polarity reversal interval GPR and prevent deterioration in quality of the signal S3 corresponding to a relatively long polarity reversal interval GPR3 by controlling supply of the drive current IOP according to the length of the polarity reversal interval GPR in the recording current waveform data DWW based on the signals to be recorded as in Example 1.

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Abstract

A magnetic recording device includes a magnetic recording medium, a microwave assisted magnetic head having a main magnetic pole for generating a recording magnetic field, and a spin torque oscillator provided near the main magnetic pole for generating a microwave magnetic field, a recording current supply part for supplying a recording current to recording coils according to recording current waveform data, a drive current supply part for supplying a drive current to the spin torque oscillator, and a drive current control part for controlling supply of the drive current by the drive current supply part based on the data. Taking into consideration as an indicator whether a polarity reversal interval included in the data exceeds a threshold time, the drive current control part controls the drive current supply part so as not to substantially lower the quality of signals recorded on the magnetic recording medium.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a magnetic recording device having a microwave assisted magnetic head, and a magnetic recording method.BACKGROUND OF THE INVENTION[0002]In the field of magnetic recording using a head and a medium, further improvement in performance of the magnetic recording medium and the magnetic head is demanded as the recording density of magnetic disc devices increases.[0003]A magnetic recording medium is a discontinuous medium consisting of a set of magnetic grains. The magnetic grains each have a single-domain structure. Each recording bit on a magnetic recording medium consists of a plurality of magnetic grains. Therefore, in order to increase the recording density, the magnetic grains must be smaller and the borders between adjacent recording bits must be less uneven. However, as the magnetic grains become smaller, the magnetic grains are less thermally stable in association with their reduced volume.[0004]A presumable measure to ...

Claims

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Application Information

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IPC IPC(8): G11B27/36G11B5/17G11B5/09G11B5/39G11B5/00
CPCG11B5/3909G11B5/09G11B5/17G11B2005/0024G11B5/02G11B5/235G11B5/3123G11B5/3146
Inventor KOBAYASHI, TATSUHIROYONEDA, SADAHARUAOYAMA, TSUTOMU
Owner TDK CORPARATION
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